Information recording method and information recording apparatus

ABSTRACT

An information recording method of recording information, in which laser light is applied to a recording medium while depending on predetermined information said laser light is modulated and the intensity of said light is controlled to form recording mark areas at which reflectivity of said recording medium changes, depending on the intensity of said applied light, wherein 
     before starting data recording, said light is applied to said recording medium at predetermined light intensity, reflection light from said recording mark areas of said recording medium is received, the amount of said reflection light is detected, and a light intensity controlling reference value is calculated on the basis of the amount of said detected light, and 
     during data recording, reflection light from said recording mark areas of said recording medium is received, the amount of said reflection light is detected, and a light intensity controlling detection value is calculated on the basis of the amount of said detected light, corrected light intensity is obtained from the difference between said light controlling intensity reference value and said light intensity controlling detection value, said light intensity controlling reference value is corrected depending on said corrected light intensity, and the intensity of said laser light is controlled so that said corrected light intensity controlling reference value substantially coincides with said light intensity controlling detection value.

This Application is a U.S. National Phase Application OF PCTInternational Application PCT/JP02/06345 filed Jun. 25, 2002.

TECHNICAL FIELD

The present invention relates to an information recording method and aninformation recording apparatus of recording information, in which laserlight is applied to a recording medium while the laser light ismodulated and the intensity of the light is controlled depending onpredetermined information to form recording mark areas at which thereflectivity of the above-mentioned recording medium changes dependingon the intensity of the applied light.

BACKGROUND TECHNOLOGY

With the widespread use of multimedia in recent years, a write-onceoptical disk, i.e., CD-R, and a rewritable optical disk, i.e., CD-RW,have come into widespread use quickly, and optical disks having largercapacities, such as a write-once optical disk, i.e., DVD-R, andrewritable optical disks, i.e., DVD-RW and DVD-RAM, are put to practicaluse and beginning to be used widely. In order to record information,each of these optical disks is used with an informationrecording/reproducing apparatus including an optical pickup systemhaving a semiconductor laser as a light source. Various technologicaldevelopments have been carried out to enhance and stabilize therecording and reproduction performance of these informationrecording/reproducing apparatuses. A semiconductor laser power controltechnology is one of the technologies, and numerous systems have beenproposed. In particular, in the case of the write-once optical disk,since no data can be rewritten, it becomes important how a stablerecording state can be maintained. The laser power control systemsincludes, for example, a system referred to as APC (Auto Power Control)wherein part of the amount of outgoing laser light is detected and laserpower is controlled so that outgoing power is maintained constant, and asystem referred to as R-OPC (Running-Optimum Power Control) wherein theamount of reflection light from a recording medium is detected duringrecording, and laser power is controlled so that the amount ofreflection light from the recording mark areas of the recording mediumbecomes a predetermined amount of light.

For example, as disclosed in Japanese Patent Application No.2000-295734, a system is proposed wherein laser power is controlled incombination with APC and R-OPC by using the recording waveform of amulti-pulse train with pulses having different widths for mark areas.

FIG. 7 is a block diagram showing a prior art information recordingapparatus of carrying out laser power control in combination with APCand R-OPC, and FIG. 8 shows the detection signal waveforms for APC andthe detection signal waveforms for R-OPC in the prior art informationrecording apparatus that uses the recording waveform of a multi-pulsetrain with pulses having different widths for mark areas.

Numeral 101 designates an optical disk capable of recording andreproducing information. Numeral 102 designates a spindle motor ofrotating the optical disk 101.

Numeral 103 designates a laser diode capable of emitting light by usinga multi-pulse train with pulses having different widths for mark areasduring recording on the optical disk 101. Numeral 104 designates a beamsplitter of separating the outgoing light of the laser diode 103 and thereturn light from the optical disk 101. Numeral 105 designates anobjective lens of gathering laser light in recordable or reproducibleareas of the optical disk 101.

Numeral 106 designates a light amount monitoring photodetector ofdetecting part of the outgoing light emitted from the laser diode 103.Numeral 107 designates an I/V conversion circuit of converting thecurrent output of the light amount monitoring photodetector 106 into avoltage.

Numeral 108 designates a low-pass filter (LPF) of attenuating thefrequency band of the output of the I/V conversion circuit 107. Numeral109 designates a voltage amplifier (AMP) of amplifying the currentoutput of the light amount monitoring photodetector 106. Numeral 110designates a sample-and-hold circuit (S/H) of sampling and holding theoutput of the LPF 108 at predetermined timing. Numeral 111 designates asample-and-hold circuit (S/H) of sampling and holding the output of theAMP 109 at predetermined timing.

Numeral 112 designates an mp detector of detecting the output of the S/H110 as the average power of recording light emission for a multi-pulsetrain.

Numeral 113 designates an sp detector of detecting the output of the S/H111 as the bias power of recording light emission for a multi-pulsetrain.

Numeral 114 designates a peak power control circuit of controlling thepeak power of the recording light emission for a multi-pulse train.

Numeral 115 designates a bias power control circuit of controlling thebias power of the recording light emission for a multi-pulse train.Numeral 116 designates an LD drive circuit of driving the laser diode103 to emit light by using power and a multi-pulse train with pulseshaving different widths controlled by the peak power control circuit 114and the bias power control circuit 115.

Numeral 117 designates a plurality of return light detectingphotodetectors of detecting return light from the optical disk 101.Numeral 118 designates a plurality of I/V conversion circuits ofconverting each of the current outputs of the plurality of return lightdetecting photodetectors 117 into a voltage.

Numeral 119 designates an RF adder of adding the outputs of theplurality of I/V conversion circuits 118. Numeral 120 designates alow-pass filter (LPF) of attenuating the frequency band of the output ofthe RF adder 119. Numeral 121 designates a voltage amplifier (AMP) ofamplifying the output of the LPF 120. Numeral 122 designates asample-and-hold circuit (S/H) of sampling and holding the output of theLPF 120 at predetermined timing. Numeral 123 designates asample-and-hold circuit (S/H) of sampling and holding the output of theAMP 121 at predetermined timing.

Numeral 124 designates an MP detector of detecting the output of the S/H122 as the average amount of return light from the mark areas of theoptical disk 101 during recording.

Numeral 125 designates an SP detector of detecting the output of the S/H123 as the amount of return light from the space (non-mark) areas of theoptical disk 101 during recording.

Numeral 126 designates a B/A calculation circuit of calculating a B/Avalue used as a parameter required for the R-OPC operation from theoutput of the MP detector 124 and the output of the SP detector 125.Numeral 127 designates a CPU of calculating the correction amount of thepeak power on the basis of the output of the B/A calculation circuit 126and of issuing a target peak power command to the peak power controlcircuit 114.

In accordance with the configuration described above, the operation ofcarrying out laser power control in combination with ARC and R-OPC willbe described below by using the detection signal waveforms for APC andthe detection signal waveforms for R-OPC shown in FIG. 8.

In the case when the record data shown in FIG. 8(a) is converted into amulti-pulse train with pulses having different widths shown in FIG. 8(b)and when the laser diode 103 is controlled by predetermined peak powerand predetermined bias power, first, as the APC operation, the lightemission waveform shown in FIG. 8(c) is detected by the light amountmonitoring photodetector 106, the output of the trailing end of themulti-pulse train becomes the mp level shown in FIG. 8(d) by the LPF108, and mp is sampled and held by the S/H 110 and detected by the mpdetector 112 as average power formed of the pulse width ratio of themulti-pulse train and converted from the pulse width ratio of themulti-pulse train, whereby the peak power is detected.

Furthermore, the sp level shown in FIGS. 8(c) and 8(d) is amplified bythe AMP 109 and then sampled and held by the S/H 111 and detected by thesp detector 113 as bias power. The peak power control circuit 114 andthe bias power control circuit 115 control the laser power so that thepeak power and the bias power obtained from mp and sp becomepredetermined values.

Next, the R-OPC operation will be described. Although the control iscarried out on the basis of the predetermined power values by the APCoperation, an optimum recording power value differs depending onrecording areas and recording states owing to variations in recordingsensitivity because of differences in recording areas on the recordingface of the optical disk 101. Hence, in addition to the APC operation,another power control operation is required to be carried out so thatthe optimum recording power is obtained in the states wherein recordingis performed.

This power control operation is R-OPC, and the correction amount of thepower is calculated while the return light during recording is detected.FIG. 8(e) shows the waveform of return light during recording, generatedfrom the return light detecting photodetectors 117, the I/V conversioncircuits 118 and the RF adder 119.

“A” in FIG. 8(e) designates the maximum level of the return light in astate wherein no mark is formed in the mark areas of the recording faceof the optical disk 101 during light emission at the peak power, and “B”designates the maximum level of the return light in a mark forming stateduring light emission at the peak power. “A” is substantiallyproportional to the reflectivity of the non-recording areas of theoptical disk 101 and the peak power, and “B” is based on therelationship between the reflectivity being different depending on theforming state of the recording marks of the optical disk 101 and thepeak power. The value (B/A) obtained by dividing B by A is detected, andthe peak power is controlled so that a predetermined B/A value isobtained.

However, as the pulse width of the multi-pulse train becomes shorter, itis difficult to directly detect the A and B values; just like the APCoperation, as shown in FIG. 8(f), the output of the trailing end of themulti-pulse train becomes an MP level by the LPF 120, and MP is sampledand held by the S/H 122 and detected by the MP detector 124 as anaverage return light amount formed of the pulse width ratio of themulti-pulse train and converted from the pulse width ratio of themulti-pulse train, whereby the B value shown in FIG. 8(e) is detected.

Furthermore, the SP level shown in FIGS. 8(e) and 8(f) is amplified bythe AMP 121 and then sampled and held by the S/H 123 and detected by theSP detector 125 as the amount of return light at the bias power, and theA value is detected from the ratio between the peak power and the biaspower. After the B/A value is calculated, it is compared with thepredetermined B/A value at the optimum recording power supplied to theoptical disk 101, a peak power correction amount of obtaining theabove-mentioned predetermined B/A value is obtained by the CPU 127, andthe correction of the peak power is commanded to the peak power controlcircuit 114, whereby proper power control is carried out. FIG. 8(g)shows examples of recording marks recorded by the laser power controlledby the above-mentioned APC and R-OPC operations.

As a result, even when the recording sensitivity varies depending on thedifference in the recording areas of the recording face of the opticaldisk 101, the mark forming state during recording can always be judgedby using the return light and the B/A value, whereby it is possible tocontrol the laser power so that an optimum recording state can beattained.

However, when stresses, such as defocusing, off-tracking and tilting,are changed during recording, not only the optimum recording power ischanged, but also the detection of the return light amount is affected,and the B/A value used as the control target value of R-OPC is changedwith respect to the optimum recording power supplied to the opticaldisk.

FIG. 9 shows an example of the relationship of the change of the optimumB/A value depending on the change of stress. This relationship isdiscovered by the inventors. FIG. 9 shows the dependence of the B/Avalue for the recording power on radial tilting indicating tilting inthe radial direction of the disk, and shows that the B/A value for theoptimum recording power increases as radial tilting increases.

The recording peak power control operation by R-OPC will be described byusing FIG. 14 showing the dependence of the R-OPC detection signal onpower. {circle around (1)} in FIG. 14 designates a point that indicatesthe optimum recording power Po and the R-OPC detection signal B/Ai at Poin a characteristic curve A indicating the relationship between thepower and B/A immediately before or after recording, and B/Ai is acontrol target value of R-OPC during recording. {circle around (2)}designates a point that indicates the optimum recording power Po at thetime of the characteristic curve A and the R-OPC detection signal B/An1on a characteristic curve B in the case when the change of the stress isnot caused but only the variation of the disk sensitivity is caused.{circle around (2)}′ designates a point that indicates the true optimumrecording power P1 and the R-OPC detection signal B/Ai at P1 in thecharacteristic curve B, and the B/Ai is the same B/A value as that of{circle around (1)} of the characteristic curve A. {circle around (3)}designates a point that indicates the optimum recording power Po at thetime of the characteristic curve A and the R-OPC detection signal B/An2in a characteristic curve C in the case when tilting, one of thestresses, is caused significantly. {circle around (3)}′ designates apoint that indicates the true optimum recording power P2′ and the R-OPCdetection signal B/Ai′ at P2′ in the characteristic curve C. {circlearound (3)}″ designates a point that indicates recording peak power P2for B/Ai at {circle around (1)} and {circle around (2)}′ in thecharacteristic curve C. In the R-OPC operation in the characteristiccurve B wherein the change of stress is not caused, since the R-OPCdetection signal B/An1 at the power Po during recording is deviated fromthe control target value B/Ai, recording is continued while the power ischanged to the power P1 obtained by adding a correction amount Pc1 to Poso that convergence is performed to the control target value. Since P1is the optimum recording power value, the quality of recording ismaintained.

Next, in the R-OPC operation in the characteristic curve C whereintilting, one of the stresses, is caused significantly, since the R-OPCdetection signal B/An2 at the power Po during recording is deviated fromthe control target value B/Ai, recording is continued while the power ischanged to the power P2 obtained by adding a correction amount Pc2 to Poso that convergence is performed to the control target value. Since P2is larger than the optimum recording power value P2′, the quality ofrecording is not maintained.

In other words, when power control is carried out with the B/A valueused as the R-OPC control target value fixed at a constant value,control is carried out by using power excessively larger than theoptimum recording power.

As a result, stable recording becomes difficult, and data reproductionafter recording is affected significantly.

DISCLOSURE OF THE INVENTION

Accordingly, in consideration of the above-mentioned problems, thepresent invention is intended to provide an information recording methodand an information recording apparatus capable of recording on anoptical disk at optimum recording power, even when stresses, such asdefocusing, off-tracking and tilting, are changed during recording.

To solve the above problems, a first aspect of the present invention isan information recording method of recording information, in which laserlight is applied to a recording medium while depending on predeterminedinformation said laser light is modulated and the intensity of saidlight is controlled to form recording mark areas at which reflectivityof said recording medium changes, depending on the intensity of saidapplied light, wherein

before starting data recording, said light is applied to said recordingmedium at predetermined light intensity, reflection light from saidrecording mark areas of said recording medium is received, the amount ofsaid reflection light is detected, and a light intensity controllingreference value is calculated on the basis of the amount of saiddetected light, and

during data recording, reflection light from said recording mark areasof said recording medium is received, the amount of said reflectionlight is detected, and a light intensity controlling detection value iscalculated on the basis of the amount of said detected light, correctedlight intensity is obtained from the difference between said lightcontrolling intensity reference value and said light intensitycontrolling detection value, said light intensity controlling referencevalue is corrected depending on said corrected light intensity, and theintensity of said laser light is controlled so that said corrected lightintensity controlling reference value substantially coincides with saidlight intensity controlling detection value.

Further, a second aspect of the present invention is an informationrecording method, wherein said light intensity controlling referencevalue to be used for calculating said corrected light intensity isrenewed to said corrected light intensity controlling reference value.

Further, a third aspect of the present invention is an informationrecording method of recording information, in which laser light isapplied to a recording medium on which light intensity suited for markformation changes owing to the change of the wavelength of said laserlight depending on temperature change while depending on predeterminedinformation said laser light is modulated and the intensity of saidlight is controlled to form recording mark areas at which reflectivityof said recording medium changes, depending on the intensity of saidapplied light, wherein

before starting data recording, said light is applied to said recordingmedium at predetermined light intensity, reflection light from saidrecording mark areas of said recording medium is received, the amount ofsaid reflection light is detected and laser vicinity temperature isdetected simultaneously, a light intensity controlling reference valueis calculated on the basis of the amount of said detected light, and thedetected temperature is memorized as a reference temperature, and duringdata recording, reflection light from said recording mark areas of saidrecording medium is received, the amount of said reflection light isdetected, a light intensity controlling detection value is calculated onthe basis of the amount of said detected light and laser vicinitytemperature is detected simultaneously, first corrected light intensityis obtained from the difference between said light controlling intensityreference value and said light intensity controlling detection value,second corrected light intensity is obtained from the difference betweensaid detected temperature and said reference temperature, lightintensity obtained by subtracting said second corrected light intensityfrom said first corrected light intensity is obtained as temperaturecorrected light intensity, said light intensity controlling referencevalue is corrected depending on said temperature corrected lightintensity, and the intensity of said laser light is controlled so thatsaid corrected light intensity controlling reference value substantiallycoincides with said light intensity controlling detection value.

Further, a fourth aspect of the present invention is an informationrecording method in accordance with the third aspect of the presentinvention, wherein said light intensity controlling reference value tobe used for calculating said temperature corrected light intensity isrenewed to said corrected light intensity controlling reference value.

Further, a fifth aspect of the present invention is an informationrecording method in accordance with the first or the third aspect of thepresent invention, wherein

calculation of said light intensity controlling reference value and saidlight intensity controlling detection value is carried out

by detecting the average output of the amount of the reflection light atsaid recording mark areas after a predetermined time based on a laserlight modulation signal has passed, by obtaining the maximum value ofthe amount of the reflection light at said recording mark areas from thedetection value, by calculating the maximum value of the amount of thereflection light at the peak value of the light intensity having beenset on the basis of the detection result of the amount of the reflectionlight at areas, other than recording mark areas, irradiated with lightat light intensity not contributing to recording mark formation, and bydividing the maximum value of the amount of the reflection light in saidrecording mark areas by the calculated maximum value of the amount ofthe reflection light at the peak value of the light intensity.

Further, a sixth aspect of the present invention is an informationrecording method in accordance with the first or the third aspect of thepresent invention, wherein

a corrected light intensity correction table indicating the relationshipof a reference value correction amount with respect to said correctedlight intensity in each type of recording medium is memorized inadvance, and said light intensity controlling reference value dependingon said corrected light intensity is corrected on the basis of saidcorrected light intensity correction table after discrimination of thetype of the recording medium.

Further, a seventh aspect of the present invention is an informationrecording method in accordance with the third aspect of the presentinvention, wherein

a light intensity temperature correction table indicating therelationship of the change amount of the light intensity suited for markformation with respect to temperature in each type of recording mediumis memorized in advance, and said second corrected light intensity isobtained on the basis of the difference between said detectedtemperature and said reference temperature and said light intensitytemperature correction table.

Further, an eighth aspect of the present invention is an informationrecording method of recording information, in which laser light isapplied to a recording medium while depending on predeterminedinformation said laser light is modulated and the intensity of saidlight is controlled to form recording mark areas at which reflectivityof said recording medium changes depending on the intensity of saidapplied light, wherein

before starting data recording, said light is applied to said recordingmedium at predetermined light intensity, reflection light from saidrecording mark areas of said recording medium is received, the amount ofsaid reflection light is detected, and a light intensity controllingreference value is calculated on the basis of the amount of the detectedlight, and

during data recording, reflection light from said recording mark areasof said recording medium is received, the amount of said reflectionlight is detected, a light intensity controlling detection value iscalculated on the basis of the amount of said detected light and astress affecting recording or reproduction on said recording medium asthe change of light intensity simultaneously, said light intensitycontrolling reference value is corrected depending on said stress, andthe intensity of said laser light is controlled so that said correctedlight intensity controlling reference value substantially coincides withsaid light intensity controlling detection value.

Further, a ninth aspect of the present invention is an informationrecording method in accordance with the eighth aspect of the presentinvention, wherein

a stress correction table indicating the relationship of a referencevalue correction amount with respect to said stress in each type ofrecording medium is memorized in advance, and said light intensitycontrolling reference value depending on said stress is corrected on thebasis of said stress correction table after discrimination of the typeof the recording medium.

Further, a tenth aspect of the present invention is an informationrecording apparatus of recording information, in which laser light isapplied to a recording medium while depending on predeterminedinformation said laser light is modulated and the intensity of saidlight is controlled to form recording mark areas at which reflectivityof said recording medium changes, depending on the intensity of saidapplied light, comprising:

outgoing light amount controlling means of detecting the amount ofoutgoing laser light and of controlling the amount of the outgoing laserlight so as to obtain a predetermined power value,

reflection light amount detecting means of receiving reflection lightfrom the recording mark areas of said recording medium and of detectingthe amount of the reflection light,

light intensity controlling detection signal generating means ofgenerating a light intensity controlling detection signal on the basisof the amount of the detected light of said reflection light amountdetecting means,

reference value generating means of applying light in advance to saidrecording medium at predetermined light intensity before starting datarecording and of generating a light intensity controlling referencevalue from said light intensity controlling detection signal,

light intensity controlling detection value generating means ofgenerating a light intensity controlling detection value from said lightintensity controlling detection signal during data recording,

switching means of switching the output of said light intensitycontrolling detection signal to said reference value generating means orsaid light intensity controlling detection value generating means,

reference value correcting means of obtaining corrected light intensityfrom the difference between said reference value and said lightintensity controlling detection value and of correcting said referencevalue depending on said corrected light intensity, and

corrected power value generating means of generating a corrected powervalue from the difference between said reference value corrected by saidreference value correcting means and said light intensity controllingdetection value and of outputting said corrected power value to saidoutgoing light amount controlling means.

Further, an eleventh aspect of the present invention is an informationrecording apparatus of recording information, in which laser light isapplied to a recording medium on which light intensity suited for markformation changes owing to the change of the wavelength of said laserlight depending on temperature change while said laser light ismodulated and the intensity of said light is controlled depending onpredetermined information to form recording mark areas at which thereflectivity of said recording medium changes depending on the intensityof said applied light, comprising:

outgoing light amount controlling means of detecting the amount ofoutgoing laser light and of controlling the amount of the outgoing laserlight so as to obtain a predetermined power value,

reflection light amount detecting means of receiving reflection lightfrom the recording mark areas of said recording medium and of detectingthe amount of the reflection light,

light intensity controlling detection signal generating means ofgenerating a light intensity controlling detection signal on the basisof the amount of the detected light of said reflection light amountdetecting means,

temperature detecting mans of detecting laser vicinity temperature,

reference value generating means of applying light in advance to saidrecording medium at predetermined light intensity before starting datarecording and of generating light intensity controlling reference valuefrom said light intensity controlling detection signal,

reference temperature memorizing means of memorizing the result ofdetection after the laser vicinity temperature at the time of thegeneration of said reference value is detected by said temperaturedetecting means,

light intensity controlling detection value generating means ofgenerating a light intensity controlling detection value from said lightintensity controlling detection signal during data recording,

detected temperature memorizing means of memorizing the result ofdetection after the laser vicinity temperature at the time of thegeneration of said light intensity controlling detection value isdetected by said temperature detecting means,

switching means of switching the output of said light intensitycontrolling detection signal to said reference value generating means orsaid light intensity controlling detection value generating means,

first corrected light intensity generating means of calculating firstcorrected light intensity from the difference between said referencevalue and said light intensity controlling detection value,

second corrected light intensity generating means of calculating secondcorrected light intensity from the difference between said detectedtemperature and said reference temperature,

temperature corrected light intensity generating means of generatingtemperature corrected light intensity by subtracting said secondcorrected light intensity from said first corrected light intensity,

reference value correcting means of correcting said reference valuedepending on said temperature corrected light intensity, and

corrected power value generating means of generating a corrected powervalue from the difference between said reference value corrected by saidreference value correcting means and said light intensity controllingdetection value and of outputting said corrected power value to saidoutgoing light amount controlling means.

Further, a twelfth aspect of the present invention us an informationrecording apparatus in accordance with the tenth or the eleventh aspectof the present invention wherein said light intensity controllingdetection signal generating means comprises:

a low-pass filter of averaging the output of said reflection lightamount detecting means,

a sample-and-hold circuit of detecting the output of said low-passfilter after a predetermined time based on a laser light modulationsignal,

mark area reflection light amount maximum value generating means ofobtaining the maximum value of the amount of reflection light atrecording mark areas from a value detected by said sample-and-holdcircuit and the duty ratio of outgoing power contributing to markformation,

peak power reflection light amount maximum value generating means ofcalculating the peak amount of reflection light at the peak value oflight intensity having been set on the basis of the result of thedetection of the amount of reflection light at areas, other than therecording mark areas, irradiated with light at light intensity notcontributing to recording mark formation, and

a division circuit of dividing said maximum value of the amount ofreflection light at said recording mark areas by the maximum value ofthe peak power amount of reflection light and of generating a lightintensity controlling detection signal.

A thirteenth aspect of the present invention is an information recordingapparatus in accordance with the tenth or the eleventh aspect of thepresent invention, comprising recording medium type discrimination meansand means of memorizing corrected light intensity correction tableindicating the relationship of the correction amount of said referencevalue with respect to said corrected light intensity in each type ofrecording medium in advance.

A fourteenth aspect of the present invention is an information recordingapparatus in accordance with the tenth or the eleventh aspect of thepresent invention, comprising recording medium type discrimination meansand means of memorizing light intensity temperature correction tableindicating the relationship of the change amount of light intensitysuited for mark formation with respect to temperature in each type ofrecording medium in advance.

A fifteenth aspect of the present invention is an information recordingapparatus of recording information, in which laser light is applied to arecording medium while depending on predetermined information said laserlight is modulated and the intensity of said light is controlled to formrecording mark areas at which reflectivity of said recording mediumchanges, depending on the intensity of said applied light, comprising:

outgoing light amount controlling means of detecting the amount ofoutgoing laser light and of controlling the amount of the outgoing laserlight so as to obtain a predetermined power value,

reflection light amount detecting means of receiving reflection lightfrom the recording mark areas of said recording medium and of detectingthe amount of the reflection light,

light intensity controlling detection signal generating means ofgenerating a light intensity controlling detection signal on the basisof the amount of the detected light of said reflection light amountdetecting means,

reference value generating means of applying light in advance to saidrecording medium at predetermined light intensity before starting datarecording and of generating a light intensity controlling referencevalue from said light intensity controlling detection signal,

light intensity controlling detection value generating means ofgenerating a light intensity controlling detection value from said lightintensity controlling detection signal during data recording,

switching means of switching the output of said light intensitycontrolling detection signal to said reference value generating means orsaid light intensity controlling detection value generating means,

stress detecting means of detecting stress affecting recording orreproduction on said recording medium as the change of light intensity,

reference value correcting means of correcting said light intensitycontrolling reference value depending on said stress,

corrected power value generating means of generating a corrected powervalue from the difference between said reference value corrected by saidreference value correcting means and said light intensity controllingdetection value and of outputting said corrected power value to saidoutgoing light amount controlling means.

A sixteenth aspect of the present invention is an information recordingapparatus in accordance with the fifteenth aspect of the presentinvention, comprising recording medium type discrimination means andmeans of memorizing stress correction table indicating the relationshipof the correction amount of said reference value with respect to saidstress in each type of recording medium in advance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the configuration of an informationrecording apparatus in accordance with a first embodiment of the presentinvention;

FIG. 2 is a block diagram showing the configuration of an informationrecording apparatus in accordance with a second embodiment of thepresent invention;

FIG. 3 is a view showing the relationship between temperature and laserwaveform;

FIG. 4 is a view showing the dependence of the recording sensitivity ofan optical disk on waveform;

FIG. 5 is a block diagram showing the configuration of an informationrecording apparatus in accordance with a third embodiment of the presentinvention;

FIG. 6 is a block diagram showing the configuration of an informationrecording apparatus in accordance with a fourth embodiment of thepresent invention;

FIG. 7 is a block diagram showing the configuration of the prior artinformation recording apparatus;

FIG. 8 is a view showing the detection signal waveform for APC and thedetection signal waveform for R-OPC;

FIG. 9 is a view showing the relationship of the change of the optimumB/A value depending on the change of stress;

FIG. 10 is a flowchart showing the operation of the first embodiment ofthe present invention;

FIG. 11 is a flowchart showing the operation of the second embodiment ofthe present invention;

FIG. 12 is a flowchart showing the operation of the third embodiment ofthe present invention;

FIG. 13 is a flowchart showing the operation of the fourth embodiment ofthe present invention;

FIG. 14 is a view showing the dependence of the R-OPC detection signalon power in the recording peak power control operation by R-OPC;

FIG. 15 is a view showing the relationship of a B/Ai reference valuewith respect to corrected light intensity Pc;

FIG. 16 is a view showing the relationship among recording power, B/Aand B/Ai reference value correction coefficient k; and

FIG. 17 is a view showing the relationship of the B/Ai reference valuewith respect to temperature corrected light intensity Pt.

FIG. 18 is a table showing corrected light intensity correction andlight intensity temperature correction.

EXPLANATION OF NUMERALS

-   1 optical disk-   2 spindle motor-   3 laser diode-   4 beam splitter-   5 objective lens-   6 light amount monitoring photodetector-   7 I/V conversion circuit-   8 LPF-   9 AMP-   10, 11 S/H-   12 mp detector-   13 sp detector-   14 peak power control circuit-   15 bias power control circuit-   16 LD drive circuit-   17 return light detecting photodetector-   18 I/V conversion circuit-   19 RF adder-   20 LPF-   21 AMP-   22, 23 S/H-   24 MP detector-   25 SP detector-   26 B/A calculation circuit-   27 learning LPF-   28 averaging circuit-   29 (B/A)i detector-   30 controlling LPF-   31 (B/A)n detector-   32 38, 40, 42, 127 CPU-   33 switch-   34 comparator-   35 (B/A)i correction circuit-   36 corrected power calculation circuit-   37 temperature change detector-   39 disk type discrimination circuit-   41 stress detector-   101 optical disk-   102 spindle motor-   103 laser diode-   104 beam splitter-   105 objective lens-   106 light amount monitoring photodetector-   107 I/V conversion circuit-   108 LPF-   109 AMP-   110, 11 S/H-   112 mp detector-   113 sp detector-   114 peak power control circuit-   115 bias power control circuit-   116 LD drive circuit-   117 return light detecting photodetector-   118 I/V conversion circuit-   119 RF adder-   120 LPF-   121 AMP-   122, 123 S/H-   124 MP detector-   125 SP detector-   126 B/A calculation circuit

THE BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments in accordance with the present invention will be describedbelow referring to the drawings.

The same components in the embodiments are designated by the samenumerals.

(First Embodiment)

First, a first embodiment will be described.

FIG. 1 is a block diagram showing the configuration of an informationrecording apparatus in accordance with this embodiment. FIG. 10 is aflowchart showing the operation of this embodiment.

The information recording method and information recording apparatus inaccordance with this embodiment will be described by using FIG. 1 andFIG. 10.

Numeral 1 designates an optical disk capable of recording andreproducing information. Numeral 2 designates a spindle motor ofrotating the optical disk 1. Numeral 3 designates a laser diode capableof emitting light by using a multi-pulse train with pulses havingdifferent widths for mark areas during recording on the optical disk 1.Numeral 4 designates a beam splitter of separating the outgoing light ofthe laser diode 3 and the return light from the optical disk 1. Numeral5 designates an objective lens of gathering laser light in recordable orreproducible areas of the optical disk 1.

Numeral 6 designates a light amount monitoring photodetector ofdetecting part of the outgoing light emitted from the laser diode 3.Numeral 7 designates an I/V conversion circuit of converting the currentoutput of the light amount monitoring photodetector 6 into a voltage.

Numeral 8 designates a low-pass filter (LPF) of attenuating thefrequency band of the output of the I/V conversion circuit 7. Numeral 9designates a voltage amplifier (AMP) of amplifying the current output ofthe light amount monitoring photodetector 6. Numeral 10 designates asample-and-hold circuit (S/H) of sampling and holding the output of theLPF 8 at predetermined timing. Numeral 11 designates a sample-and-holdcircuit (S/H) of sampling and holding the output of the AMP 9 atpredetermined timing. Numeral 12 designates an mp detector of detectingthe output of the S/H 10 as the average power of recording lightemission for a multi-pulse train.

Numeral 13 designates an sp detector of detecting the output of the S/H11 as the bias power of recording light emission for a multi-pulsetrain. Numeral 14 designates a peak power control circuit of controllingthe peak power of the recording light emission for a multi-pulse train.Numeral 15 designates a bias power control circuit of controlling thebias power of the recording light emission for a multi-pulse train.Numeral 16 designates an LD drive circuit of driving the laser diode 3to emit light by using power and a multi-pulse train with pulses havingdifferent widths controlled by the peak power control circuit 14 and thebias power control circuit 15.

Numerals 6 to 13 designate examples of outgoing light amount controllingmeans of detecting the amount of the outgoing laser light and ofcontrolling the amount of the outgoing laser light to obtain apredetermined power value.

Numeral 17 designates a plurality of return light detectingphotodetectors of detecting return light from the optical disk 1.Numeral 18 designates a plurality of I/V conversion circuits ofconverting each of the current outputs of the plurality of return lightdetecting photodetectors 17 into a voltage.

Numeral 19 designates an RF adder of adding the outputs of the pluralityof I/V conversion circuits 18. Numerals 17 to 19 designate examples ofreflection light amount detecting means of receiving reflection lightfrom the recording mark areas of a recording medium and of detecting theamount of the reflection light.

Numeral 20 designates a low-pass filter (LPF) of attenuating thefrequency band of the output of the RF adder 19. Numeral 21 designates avoltage amplifier (AMP) of amplifying the output of the LPF 20. Numeral22 designates a sample-and-hold circuit (S/H) of sampling and holdingthe output of the LPF 20 at predetermined timing. Numeral 23 designatesa sample-and-hold circuit (S/H) of sampling and holding the output ofthe AMP 21 at predetermined timing.

Numeral 24 designates an MP detector of detecting the output of the S/H22 as the average amount of return light from the mark areas of theoptical disk 1 during recording.

Numeral 25 designates an SP detector of detecting the output of the S/H23 as the amount of return light from the space (non-mark) areas of theoptical disk 1 during recording.

Numeral 26 designates a B/A calculation circuit of calculating a B/Avalue used as a parameter required for the R-OPC operation from theoutput of the MP detector 24 and the output of the SP detector 25.

Numerals 20 to 26 designate light intensity controlling detection signalgenerating means of generating a light intensity controlling detectionsignal on the basis of the amount of the detection light of theabove-mentioned reflection light amount detecting means.

Numeral 27 designates a learning LPF used as a low-pass filter ofattenuating the frequency band of the output of the B/A calculationcircuit 26.

Numeral 28 designates an averaging circuit of averaging the variationsof the output of the learning LPF 27. Numeral 29 designates a (B/A)idetector of detecting the B/A value averaged by the averaging circuit 28as a reference value used as an R-OPC control target and of holding thevalue. Numerals 27 to 29 designate reference value generating means ofapplying light to the recording medium at predetermined light intensityin advance before the start of data recording and of generating a lightintensity controlling reference value from the above-mentioned lightintensity controlling detection signal.

Numeral 30 designates a controlling LPF used as a low-pass filter ofattenuating the frequency band of the output of the B/A calculationcircuit 26.

Numeral 31 designates a (B/A)n detector of detecting the B/A value ofcarrying out R-OPC control from the output of the controlling LPF 30.

Numerals 30 to 31 designate light intensity controlling detection valuegenerating means of generating the light intensity controlling detectionvalue from the above-mentioned light intensity controlling detectionsignal at the time of data recording.

Numeral 33 designates a switch of performing switching so that theoutput of the B/A calculation circuit 26 is input to the learning LPF 27or the controlling LPF 30.

Numeral 32 designates a CPU of commanding the switch 33 to carry outswitching from the output of the B/A calculation circuit 26 to thelearning LPF 27 when generating the reference value used as the R-OPCcontrol target or to the controlling LPF 30 when generating thecontrolling detection value during data recording. Numerals 32 to 33designate switching means of selectively outputting the above-mentionedlight intensity controlling detection signal to the above-mentionedreference value generating means and light intensity controllingdetection signal generating means.

Numeral 34 designates a comparator of comparing the output of the (B/A)idetector 29 and the output of the (B/A)n detector 31 and of outputtingthe difference.

Numeral 35 designates a (B/A)i correction circuit of correcting thereference value obtained by the (B/A)i detector 29 on the basis of thedifference output of the comparator 34.

Numerals 34 to 35 designate reference value correction means ofobtaining corrected light intensity from the difference between theabove-mentioned reference value and light intensity controllingdetection value and of correcting the above-mentioned reference valuedepending on the above-mentioned corrected light intensity.

Numeral 36 designates a corrected power calculation circuit ofcalculating corrected power from the reference value used as the R-OPCcontrol target value corrected by the (B/A)i correction circuit 35 andfrom the output of the (B/A)n detector 31 and of commanding the peakpower control circuit 14 to change the peak power target value, and thiscircuit is corrected power value generating means of generating acorrected power value from the difference between the reference valuecorrected by the above-mentioned reference value correcting means andthe above-mentioned light intensity controlling detection value and ofoutputting the corrected power value to the above-mentioned outgoinglight amount controlling means.

Next, the operation of this embodiment will be described.

First, the APC operation of detecting the amount of outgoing laser lightand of controlling the laser diode 3 by using the predetermined peakpower and the predetermined bias power for multi-pulse train data withpulses having different widths is the same as the contents described inthe prior art, and thus explained in brief.

The laser light emission output detected by the light amount monitoringphotodetector 6 is detected by the LPF 8, the S/H 10 and the mp detector12 by using the output of the trailing end of the multi-pulse train ofthe light emission waveform as an mp level, the average power formed ofthe pulse width ratio of the multi-pulse train is detected, and the peakpower is detected by carrying out conversion from the pulse width ratioof the multi-pulse train. In addition, the sp level and the bias powerare detected by the AMP 9, the S/H 11 and the sp detector 13. Laserpower is controlled by the peak power control circuit 14 and the biaspower control circuit 15 so that the peak power and the bias powerobtained from mp and sp become predetermined values.

Next, the R-OPC operation will be explained.

First, before recording is carried out in the data areas of the opticaldisk 1, the operation of learning the optimum recording power and ofgenerating the reference value used as the R-OPC control target value ofthe optimum recording power by using areas other than data areas, forexample, the power calibration area, is explained.

In the power calibration area of the disk 1, recording is carried out bythe recording power obtained by the power learning. At this time, thereturn light during recording is detected by the return light detectingphotodetectors 17, the I/V conversion circuits 18 and the RF adder 19,the output of the trailing end of the multi-pulse train is detected asthe average return light amount MP level formed of the pulse width ratioof the multi-pulse train by the LPF 20, the S/H 22 and the MP detector24 and amplified by the AMP 21, the return light at the bias power issampled and held by the S/H 23, and the SP level is detected by the SPdetector 25.

With respect to the MP and SP levels detected, in the MP level, the Bvalue is calculated by the B/A calculation circuit 26 by converting thepulse width ratio of the multi-pulse train; in the SP level, the A valueis calculated from the ratio between the peak power and the bias power,and the B/A value obtained by dividing B by A is detected. Next, theoutput of the B/A value is input to the learning LPF 27 by the CPU 32and the switch 33. Since the above-mentioned B/A value is continuouslysampled and held at predetermined timing, for example, when the pulsewidth of data is 9T or more, the value detected at each time of samplingand holding varies slightly owing to the recording sensitivity in thecircumferential direction of the optical disk, the variation of thereflectivity, tilting, etc. Hence, the variation of the above-mentioneddetected B/A value is reduced by the learning LPF 27 suited for therecording time required for the generation of the reference value, andaveraged by the averaging circuit 28 by dividing the integral value ofthe sampled and held values by the number of sampling and holding times;then the (B/A)i used as the initial value of the R-OPC control targetvalue is calculated by the (B/A)i detector 29 and determined as areference value.

Next, recording in the data areas will be explained.

Even when data recording is carried out, the B/A calibration circuit 26detects the B/A value from the return light during recording just asdescribed above. The CPU 32 and the switch 33 carry out switching toinput the output of the B/A calibration circuit 26 to the controllingLPF 30. The controlling LPF is set at a frequency band best suited forthe time at which the R-OPC operation is desired to be followed. The(B/A)n value during data recording is detected by the controlling LPF 30and the (B/A)n detector 31. The difference between the initial referencevalue (B/A)i and the detection value (B/A)n is detected by thecomparator 34, and the difference information is output to the (B/A)icorrection circuit 35.

The (B/A)i correction circuit 35 carries out power conversion on thebasis of the difference information of the B/A value and calculatecorrected light intensity Pc; in the case when the corrected lightintensity Pc obtained by power conversion is not less than apredetermined power value, for example, a power value not less than thevariation of the recording sensitivity of the optical disk 1, or a powervalue of not less than ±5% of the optimum recording power obtained bypower learning in the power calibration area, the (B/A)i correctioncircuit judges that power correction factors are factors, other than thevariation in the sensitivity of the disk, including stresses, such asdefocusing, off-tracking and tilting, then corrects the reference value(B/A)i and outputs a corrected reference value (B/A)i′ to the correctedpower calculation circuit 36.

The correction of B/Ai will be described by using drawings. FIG. 15 is aview showing the relationship of the B/Ai reference value with respectto the corrected light intensity Pc. In the figure, Ps and Ps−′ indicatethe above-mentioned predetermined values; for example, it is assumedthat Ps is +5% and −Ps′ is −5% with respect to the optimum recordingpower Po during B/A learning. In the case when the corrected lightintensity Pc is Ps or more, or −Ps′ or less, a B/Ai change amount withrespect to (Pc−Ps) or (Pc+Ps′) is obtained by using the inclination k ofB/A with respect to Pc, whereby the reference value B/Ai is obtained.When Pc≧0, B/Ai′=B/Ai+k×(Pc−Ps) When Pc<0, B/Ai′=B/Ai+k×(Pc+Ps′)  (Equation 1)

The inclination k is calculated in advance from B/Ai′ with respect tothe optimum power P2′ at the time when the allowable maximum tilt of anapparatus is caused, B/Ai with respect to the optimum power Po at thetime when no tilt is caused and the above-mentioned Ps. FIG. 16 showsthe relationship among recording power, B/A and B/Ai reference valuecorrection coefficient k.k=(B/Ai′−B/Ai)/(P 2′−Po−Ps)  (Equation 2)

The inclination k which shows the relationship between theabove-mentioned corrected light intensity Pc and the correction amountof the reference value (B/A)i, and the above-mentioned predeterminedpower values Ps and −Ps have been stored in the information recordingapparatus in advance. In the case when the result obtained by powerconversion is the predetermined power value or less, the reference value(B/A)i is not corrected, and the reference value (B/A)i is output as(B/A)i′ to the corrected power calculation circuit 36.

From the result of the output of the (B/A)i correction circuit 35 andthe output of the (B/A)n detector 31, the corrected power calculationcircuit 36 obtains a peak power value Pr to be corrected actually,commands the change of the power target value to the peak power controlcircuit 14 and controls recording power.

In addition, the corrected reference value (B/A)i′ becomes the R-OPCcontrol target value of the (B/A)i detector 29, and (B/A)i used as thecontrol target value is renewed as necessary each time correction iscarried out.

As described above, in accordance with this embodiment, even if the B/Anvalue used as the R-OPC detection signal is changed by stress, powerovercorrection of the R-OPC operation due to stress change can beprevented by changing B/Ai used as the control target value, andrecording can be attained by carrying out stable and highly accuratepower control.

(Second Embodiment)

Next, a second embodiment will be described.

FIG. 2 is a block diagram showing the configuration of an informationrecording apparatus in accordance with this embodiment. FIG. 11 is aflowchart showing the operation of this embodiment.

The information recording method and information recording apparatus inaccordance with this embodiment will be described by using FIG. 2 andFIG. 11. However, components similar to those of the first embodimentare not explained.

The information recording method and information recording apparatus inaccordance with this embodiment comprises an optical disk 1, a spindlemotor 2, a laser diode 3, a beam splitter 4, an objective lens 5, alight amount monitoring photodetector 6, an I/V conversion circuit 7, anLPF 8, an AMP 9, an S/H 10, an S/H 11, an mp detector 12, an sp detector13, a peak power control circuit 14, a bias power control circuit 15, anLD drive circuit 16, return light detecting photodetectors 17, I/Vconversion circuits 18, an RF adder 19, an LPF 20, an AMP 21, an S/H 22,an S/H 23, an MP detector 24, an SP detector 25, a B/A calculationcircuit 26, a learning LPF 27, an averaging circuit 28, a (B/A)idetector 29, a controlling LPF 30, a (B/A)n detector 31, a switch 33, acomparator 34, a (B/A)i correction circuit 35, a corrected powercalculation circuit 36, a temperature change detector 37 of detectingtemperature change, and a CPU 38.

Next, the operation of this embodiment will be described. However, sincethe contents of the APC operation are similar to those of the firstembodiment, the explanation of the APC operation is omitted, and onlythe portions of the contents of the R-OPC operation, different from thefirst embodiment, are explained.

FIG. 3 shows the relationship between temperature and laser waveform.FIG. 4 shows the dependence of recording sensitivity of an optical diskon waveform.

FIG. 3 shows that the wavelength of the laser diode increasessubstantially in proportion to temperature rise.

Furthermore, in the case of an optical disk having wavelengthdependence, for example, an optical disk having a recording film of dye,FIG. 4 shows that when the recording wavelength increases, the recordingsensitivity lowers, and the optimum recording power rises. In otherwords, when a temperature change occurs, the optimum recording power ofthe optical disk having wavelength dependence is changed. The R-OPCoperation in the case when the optical disk having this wavelengthdependence is used will be explained.

In the case when a temperature change is detected by the temperaturechange detector 37, the CPU 38 obtains the change amount of the optimumrecording power with respect to the amount of the above-mentionedtemperature change, and outputs the change value of the optimumrecording power as a second corrected light intensity P2 to the (B/A)icorrection circuit 35.

The (B/A)i correction circuit 35 first carries out power conversion onthe basis of the difference information of the B/A value and obtains afirst corrected light intensity P1, then subtracts the above-mentionedcorrected light intensity P2 from the first corrected light intensity P1thereby to obtain the result of the subtraction as a temperaturecorrected light intensity Pt by calculation. Next, in the case when theabove-mentioned temperature corrected light intensity Pt is not lessthan the predetermined power value, for example, a power value not lessthan the variation of the recording sensitivity of the optical disk 1,or a power value of not less than ±5% of the optimum recording powerobtained by power learning in the power calibration area, the (B/A)icorrection circuit judges that power correction factors are factors,other than the variation in the sensitivity of the disk, includingstresses, such as defocusing, off-tracking and tilting, then correctsthe reference value (B/A)i and outputs a corrected reference value(B/A)i′ to the corrected power calculation circuit 36.

The correction of B/Ai will be described by using drawings. FIG. 17 is aview showing the relationship of the B/Ai reference value with respectto the temperature corrected light intensity Pt. In the figure, theabove-mentioned second corrected light intensity P2 is obtained bymultiplying an optimum recording power change amount Px per unittemperature, such as ° C., by a temperature change amount T° C. Px isobtained in advance by a temperature change test or the like incombination with an apparatus and a disk, memorized and stored in theapparatus.(P 2=Px×T)

Pt is obtained by subtracting the above-mentioned corrected lightintensity P2 from the first corrected light intensity P1.(Pt=P 1−P 2)

Ps and −Ps′ indicate the above-mentioned predetermined values; forexample, it is assumed that Ps is +5% and −Ps′ is −5% with respect tothe optimum recording power Po during B/A learning. In the case when thetemperature corrected light intensity Pt is Ps or more, or −Ps′ or less,a B/Ai change amount with respect to (Pt−PS) or (Pt+Ps′) is obtained byusing the inclination k of B/A with respect to Pt, whereby the referencevalue B/Ai is obtained.

 When Pt≧0, B/Ai′=B/Ai+k×(Pt−Ps)When Pt<0, B/Ai′=B/Ai+k×(Pt+Ps′)  (Equation 3)

The method of calculating the inclination k is similar to the contentsexplained in the first embodiment.

The relationship between the above-mentioned temperature corrected lightintensity Pt and the correction amount of the reference value (B/A)i andthe above-mentioned predetermined power value have been stored in theinformation recording apparatus in advance. In the case when the resultobtained by power conversion is the predetermined power value or less,the reference value (B/A)i is not corrected, and the reference value(B/A)i is output as (B/A)i′ to the corrected power calculation circuit36.

From the result of the output of the (B/A)i correction circuit 35 andthe output of the (B/A)n detector 31, the corrected power calculationcircuit 36 obtains a peak power value Pr to be corrected actually,commands the change of the power target value to the peak power controlcircuit 14 and controls recording power.

In addition, the corrected reference value (B/A)i′ becomes the R-OPCcontrol target value of the (B/A)i detector 29, and (B/A)i used as thecontrol target value is renewed as necessary each time correction iscarried out.

As described above, in accordance with this embodiment, even if the B/Anvalue used as the R-OPC detection signal is changed by stress, and evenif temperature change occurs during recording, power overcorrection ofthe R-OPC operation due to stress change can be prevented by properlychanging B/Ai used as the control target value, and recording can beattained even on an optical disk having dependence on wavelength bycarrying out stable and highly accurate power control.

(Third Embodiment)

Next, a third embodiment will be described.

FIG. 5 is a block diagram showing the configuration of an informationrecording apparatus in accordance with this embodiment. FIG. 12 is aflowchart showing the operation of this embodiment.

The information recording method and information recording apparatus inaccordance with this embodiment will be described by using FIG. 5 andFIG. 12.

However, components similar to those of the first and second embodimentsare not described.

The information recording method and information recording apparatus inaccordance with this embodiment comprises an optical disk 1, a spindlemotor 2, a laser diode 3, a beam splitter 4, an objective lens 5, alight amount monitoring photodetector 6, an I/V conversion circuit 7, anLPF 8, an AMP 9, an S/H 10, an S/H 11, an mp detector 12, an sp detector13, a peak power control circuit 14, a bias power control circuit 15, anLD drive circuit 16, return light detecting photodetectors 17, I/Vconversion circuits 18, an RF adder 19, an LPF 20, an AMP 21, an S/H 22,an S/H 23, an MP detector 24, an SP detector 25, a B/A calculationcircuit 26, a learning LPF 27, an averaging circuit 28, a (B/A)idetector 29, a controlling LPF 30, a (B/A)n detector 31, a switch 33, acomparator 34, a (B/A)i correction circuit 35, a corrected powercalculation circuit 36, a temperature change detector 37, a disk typediscrimination circuit 39 of discriminating type of disk, and a CPU 40.

Next, the operation of this embodiment will be described.

However, since the contents of the APC operation are similar to those ofthe first embodiment, the explanation of the APC operation is omitted,and only the portions of the contents of the R-OPC operation, differentfrom the first and second embodiments, are explained.

It is generally known that the change of the optimum recording power dueto temperature change and the optimum recording power due to stresschange are different depending on the type of an optical disk, forexample, the material of the recording film and the manufacturer of thedisk. This embodiment is intended to discriminate the type of the diskand to optimize the correction of the R-OPC control target valuedepending on the disk before recording is carried out on the opticaldisk.

The operation will be explained briefly.

After the information recording apparatus is turned on, an optical diskis loaded, the spindle motor is rotated, and the disk is started; atthis time, the disk type discrimination circuit 39 reads the type of thedisk loaded and the manufacturer of the disk from disk controlinformation recorded in advance, and outputs the information regardingthe type of the disk and the manufacturer of the disk to the CPU 40.

Depending on the above-mentioned type of the disk and the manufacturerof the disk, the CPU 40 has memorized and stored in advance a correctedlight intensity correction table indicating the relationship between thecorrected light intensity and the reference value (B/A)i and a lightintensity temperature correction table indicating the relationship ofthe change amount of the optimum recording power due to temperaturechange with respect to the type of the disk and the manufacturer of thedisk, and outputs the relationship between the corrected light intensityand the correction amount of the reference value (B/A)i and therelationship of the change amount of the optimum recording power due totemperature change with respect to the above-mentioned type of the diskand the manufacturer of the disk to the (B/A)i correction circuit 35.

FIG. 18 shows an example of the corrected light intensity correctiontable and the light intensity temperature correction table as describedabove. DISC type, which is as many as the number of the disk theapparatus supports, is information showing the type of the disk and themanufacturer of the disk. k is a coefficient (inclination) showing theB/Ai correction amount with respect to the corrected light intensity. Psshows the power till the B/Ai correction starts, when the correctedlight intensity is positive value. −Ps′ shows the power till the B/Aicorrection starts, when the corrected light intensity is negative value.Px shows the change amount of the optimum recording power per unittemperature.

In the case when a temperature change is detected by the temperaturechange detector 37, the CPU 40 obtains the change amount of the optimumrecording power with respect to the amount of the above-mentionedtemperature change, and outputs the change value of the optimumrecording power as a second corrected light intensity P2 to the (B/A)icorrection circuit 35.

The (B/A)i correction circuit 35 first carries out power conversion onthe basis of the difference information of the B/A value and obtains afirst corrected light intensity P1, then subtracts the above-mentionedcorrected light intensity P2 from the first corrected light intensity P1thereby to obtain the result of the subtraction as a temperaturecorrected light intensity Pt by calculation. Next, in the case when theabove-mentioned temperature corrected light intensity Pt is not lessthan the predetermined power value, for example, a power value not lessthan the variation of the recording sensitivity of the optical disk 1,or a power value of not less than ±5% of the optimum recording powerobtained by power learning in the power calibration area, the (B/A)icorrection circuit judges that power correction factors are factors,other than the variation in the sensitivity of the disk, includingstresses, such as defocusing, off-tracking and tilting, then correctsthe reference value (B/A)i and outputs a corrected reference value(B/A)i′ to the corrected power calculation circuit 36.

The relationship between the above-mentioned temperature corrected lightintensity Pt and the correction amount of the reference value (B/A)i andthe above-mentioned predetermined power value have been stored in theinformation recording apparatus in advance. In the case when the resultobtained by power conversion is the predetermined power value or less,the reference value (B/A)i is not corrected, and the reference value(B/A)i is output as (B/A)i′ to the corrected power calculation circuit36.

From the result of the output of the (B/A)i correction circuit 35 andthe output of the (B/A)n detector 31, the corrected power calculationcircuit 36 obtains a peak power value Pr to be corrected actually,commands the change of the power target value to the peak power controlcircuit 14 and controls recording power.

As described above, in accordance with this embodiment, even if the B/Anvalue used as the R-OPC detection signal is changed by stress, and evenif temperature change occurs during recording, power overcorrection ofthe R-OPC operation due to stress change can be prevented by properlychanging B/Ai used as the control target value depending on the type ofthe disk and the manufacturer of the disk, and recording can be attainedeven on various types of optical disks by carrying out stable and highlyaccurate power control.

(Fourth Embodiment)

Next, a fourth embodiment will be described.

FIG. 6 is a block diagram showing the configuration of an informationrecording apparatus in accordance with this embodiment. FIG. 13 is aflowchart showing the operation of this embodiment.

The information recording method and information recording apparatus inaccordance with this embodiment will be described by using FIG. 6 andFIG. 13. However, components similar to those of the first embodimentare not explained.

The information recording method and information recording apparatus inaccordance with this embodiment comprises an optical disk 1, a spindlemotor 2, a laser diode 3, a beam splitter 4, an objective lens 5, alight amount monitoring photodetector 6, an I/V conversion circuit 7, anLPF 8, an AMP 9, an S/H 10, an S/H 11, an mp detector 12, an sp detector13, a peak power control circuit 14, a bias power control circuit 15, anLD drive circuit 16, return light detecting photodetectors 17, I/Vconversion circuits 18, an RF adder 19, an LPF 20, an AMP 21, an S/H 22,an S/H 23, an MP detector 24, an SP detector 25, a B/A calculationcircuit 26, a learning LPF 27, an averaging circuit 28, a (B/A)idetector 29, a controlling LPF 30, a (B/A)n detector 31, a switch 33, a(B/A)i correction circuit 35, a corrected power calculation circuit 36,a stress detector 41 of detecting stress change, and a CPU 42.

Next, the operation of this embodiment will be described. However, sincethe contents of the APC operation are similar to those of the firstembodiment, the explanation of the APC operation is omitted, and onlythe portions of the contents of the R-OPC operation, different from thefirst embodiment, are explained.

The stress detector 41 is a tilt sensor capable of detecting the tiltangle between the optical disk 1 and an optical pickup including thelaser diode 3 and the objective lens 5, and outputs detected tiltinformation to the CPU 42. The CPU 42 obtains the B/A correction amountwith respect to the detected tilt angle from the B/A correction amountcorresponding to the tilt angle stored in the above-mentioned recordingapparatus in advance, and command it to the (B/A)i correction circuit35.

The (B/A)i correction circuit 35 corrects the reference value (B/A)i inaccordance with the B/A correction amount commanded by the CPU 42, andoutputs a corrected reference value (B/A)i′ to the corrected powercalculation circuit 36.

From the result of the output of the (B/A)i correction circuit 35 andthe output of the (B/A)n detector 31, the corrected power calculationcircuit 36 obtains a peak power value Pr to be corrected actually,commands the change of the power target value to the peak power controlcircuit 14 and controls recording power.

As described above, in accordance with this embodiment, even if the B/Anvalue used as the R-OPC detection signal is changed by tilting, powerovercorrection of the R-OPC operation due to tilt change can beprevented by changing B/Ai used as the control target value, andrecording can be attained by carrying out stable and highly accuratepower control.

In this embodiment, although the stress detected by the stress detectoris tilting, the stress may be defocusing or off-tracking. However, theB/A correction amount corresponding to each stress must be stored in theinformation recording apparatus in advance.

Furthermore, by providing the temperature detector of the secondembodiment, the effect similar to that of the second embodiment can beobtained.

Still further, by providing the disk type discrimination circuit of thethird embodiment, the effect similar to that of the third embodiment canbe obtained.

As clarified by the above descriptions, according to the presentinvention, in R-OPC wherein laser power control is carried out usingreturn light during recording on an optical disk, even if a stresschange, such as defocusing or off-tracking, occurs during recording,even if a temperature change occurs during recording, or even if thetype of the disk and the manufacturer of the disk is different, powerovercorrection of the R-OPC operation due to the stress change can beprevented by properly changing the R-OPC control target value, andrecording can be attained even on various types of optical disks bycarrying out stable and highly accurate power control.

1. An information recording method of recording information, in whichlaser light is applied to a recording medium white depending onpredetermined information said loser light is modulated and theintensity of said light is controlled to form recording mark areas atwhich reflectivity of said recording medium changes, depending on theintensity of said applied light, wherein before starting data recording,said light is applied to said recording medium at predetermined lightintensity, reflection tight from said recording mark areas of saidrecording medium is received, the amount of said reflection light isdetected, and a light intensity controlling reference value iscalculated on the basis of the amount of said detected light, and duringdata recording, reflection light from said recording mark areas of saidrecording medium is received, the amount of said reflection light isdetected, and a light intensity controlling detection value iscalculated on the basis of the amount of said detected light, correctedlight intensity is obtained from the difference between said lightcontrolling intensity reference value and said light intensitycontrolling detection value, said light intensity controlling referencevalue is corrected depending on said corrected light intensity, and theintensity of said laser light is controlled so that said corrected lightintensity controlling reference value substantially coincides with saidlight intensity controlling detection value.
 2. An information recordingmethod in accordance with claim 1, wherein said light intensitycontrolling reference value to be used for calculating said correctedlight intensity is renewed to said corrected light intensity controllingreference value.
 3. An information recording method of recordinginformation, in which laser light is applied to a recording medium onwhich light intensity suited for mark formation changes owing to thechange of the wavelength of said laser light depending on temperaturechange while depending on predetermined information said laser light ismodulated and the intensity of said light is controlled to formrecording mark areas at which reflectivity of said recording mediumchanges, depending on the intensity of said applied light, whereinbefore starting data recording, said light is applied to said recordingmedium at predetermined light intensity, reflection light from saidrecording mark areas of said recording medium is received, the amount ofsaid reflection light is detected and laser vicinity temperature isdetected simultaneously, a light intensity controlling reference valueis calculated on the basis of the amount of said detected light, and thedetected temperature is memorized as a reference temperature, and duringdata recording, reflection light from said recording mark areas of saidrecording medium is received, the amount of said reflection light isdetected, a light intensity controlling detection value is calculated onthe basis of the amount of said detected light and laser vicinitytemperature is detected simultaneously, first corrected light intensityis obtained from the difference between said light controlling intensityreference value and said light intensity controlling detection value,second corrected light intensity is obtained from the difference betweensaid detected temperature and said reference temperature light intensityobtained by subtracting said second corrected light intensity from saidfirst corrected light intensity is obtained as temperature correctedlight intensity, said light intensity controlling reference value iscorrected depending on said temperature corrected light intensity, andthe intensity of said laser light is controlled so that said correctedlight intensity controlling reference value substantially coincides withsaid light intensity controlling detection value.
 4. An informationrecording method in accordance with claim 3, wherein said lightintensity controlling reference value to/be used for calculating saidtemperature corrected light intensity is renewed to said corrected lightintensity controlling reference value.
 5. An information recordingmethod is accordance with claim 1 or 3, wherein calculation of saidlight intensity controlling reference value and said light intensitycontrolling detection value is carried out by detecting the averageoutput of the amount of the reflection light at said recording markareas after a predetermined time based on a laser light modulationsignal has passed, by obtaining the maximum value of the amount of thereflection light at said recording mark areas from the detection value,by calculating the maximum value of the amount of the reflection lightat the peak value of the light intensity having been set on the basis ofthe detection result of the amount of the reflection light at areas,other than recording mark areas, irradiated with light at lightintensity not contributing to recording mark formation, and by dividingthe maximum value of the amount of the reflection light in saidrecording mark areas by the calculated maximum value of the amount ofthe reflection light at the peak value of the light intensity.
 6. Aninformation recording method in accordance with claim 1 or 3, wherein acorrected light intensity correction table indicating the relationshipof a reference value correction amount with respect to said correctedlight intensity in each type of recording medium is memorized inadvance, and said light intensity controlling reference value dependingon said corrected light intensity is corrected on the basis of saidcorrected light intensity correction table after discrimination of thetype of the recording medium.
 7. An information recording method inaccordance with claim 3, wherein a light intensity temperaturecorrection table indicating the relationship of the change amount of thelight intensity suited for mark formation with respect to temperature ineach type of recording medium is memorized in advance, and said secondcorrected light intensity is obtained on the basis of the differencebetween said detected temperature and said reference temperature andsaid light intensity temperature correction table.
 8. An informationrecording method of recording information, in which laser light isapplied to a recording medium while depending on predeterminedinformation said laser light is modulated and the intensity of saidlight is controlled to form recording mark areas at which reflectivityof said recording medium changes depending on the intensity of saidapplied light, wherein before starting data recording, said light isapplied to said recording medium at predetermined light intensity,reflection light from said recording mark areas of said recording mediumis received, the amount of said reflection light is detected, and alight intensity controlling reference value is calculated on the basisof the amount of the detected light, and during data recording,reflection light from said recording mark areas of said recording mediumis received, the amount of said reflection light is detected, a lightintensity controlling detection value is calculated on the basis of theamount of said detected light and a stress affecting recording orreproduction on said recording medium as the change of light intensitysimultaneously, said light intensity controlling reference value iscorrected depending on said stress, and the intensity of said laserlight is controlled so that said corrected light intensity controllingreference value substantially coincides with said light intensitycontrolling detection value.
 9. An information recording method inaccordance with claim 8, wherein a stress correction table indicatingthe relationship of a reference value correction amount with respect tosaid stress in each type of recording medium is memorized in advance,and said light intensity controlling reference value depending on saidstress is corrected on the basis of said stress correction table afterdiscrimination of the type of the recording medium.
 10. An informationrecording apparatus of recording information, in which laser light isapplied to a recording medium while depending on predeterminedinformation said laser light is modulated and the intensity of saidlight is controlled to form recording mark areas at which reflectivityof said recording medium changes, depending on the intensity of saidapplied light, comprising: outgoing light around controlling means ofdetecting the amount of outgoing laser light and of controlling theamount of the outgoing laser light so as to obtain a predetermined powervalue, reflection light amount detecting means of receiving reflectionlight from the recording mark areas of said recording medium and ofdetecting the amount of the reflection light, light intensitycontrolling detection signal generating means of generating a lightintensity controlling detection signal on the basis of the amount of thedetected light of said reflection light amount detecting means,reference value generating means of applying light in advance to saidrecording medium at predetermined light intensity before starting datarecording and of generating a light intensity controlling referencevalue from said light intensity controlling detection signal, lightintensity controlling detection value generating means of generating alight intensity controlling detection value from said light intensitycontrolling detection signal during data recording, switching means ofswitching the output of said light intensity controlling detectionsignal to said reference value generating means or said light intensitycontrolling detection value generating means, reference value correctingmeans of obtaining corrected light intensity from the difference betweensaid reference value and said light intensity controlling detectionvalue and of correcting said reference value depending on said correctedlight intensity, and corrected power value generating means ofgenerating a corrected power value from the difference between saidreference value corrected by said reference value correcting means andsaid light intensity controlling detection value and of outputting saidcorrected power value to said outgoing light amount controlling means.11. An information recording apparatus of recording information, inwhich laser light is applied to a recording medium on which lightintensity suited for mark formation changes owing to the change of thewavelength of said laser light depending on temperature change whilesaid laser light is modulated and the intensity of said light iscontrolled depending on predetermined information to form recording markareas at which the reflectivity of said recording medium changesdepending on the intensity of said applied light, comprising; outgoinglight amount controlling means of detecting the amount of outgoing laserlight and of controlling the amount of the outgoing laser light so as toobtain a predetermined power value, reflection light amount detectingmeans of receiving reflection light from the recording mark areas ofsaid recording medium and of detecting the amount of the reflectionlight, light intensity controlling detection signal generating means ofgenerating a light intensity controlling detection signal on the basisof the amount of the detected light of said reflection light amountdetecting means, temperature detecting means of detecting laser vicinitytemperature, reference value generating means of applying light inadvance to said recording medium at predetermined light intensity beforestarting data recording and of generating light intensity controllingreference value from said light intensity controlling detection signal,reference temperature memorizing means of memorizing the result ofdetection after the laser vicinity temperature at the time of thegeneration of said reference value is detected by said temperaturedetecting means, light intensity controlling detection value generatingmeans of generating a light intensity controlling detection value fromsaid light intensity controlling detection signal during data recording,detected temperature memorizing means of memorizing the result ofdetection after the laser vicinity temperature at the time of thegeneration of said light intensity controlling detection value isdetected by sold temperature detecting means, switching means ofswitching the output of said light intensity controlling detectionsignal to said reference value generating means or sold light intensitycontrolling detection value generating means, first corrected lightintensity generating means of calculating first corrected lightintensity from the difference between said reference value and saidlight intensity controlling detection value, second corrected lightintensity generating means of calculating second corrected lightintensity from the difference between said detected temperature and saidreference temperature, temperature corrected light intensity generatingmeans of generating temperature corrected light intensity by subtractingsaid second corrected light intensity from said first corrected lightintensity, reference value correcting means of correcting said referencevalue depending on said temperature corrected light intensity, andcorrected power value generating means of generating a corrected powervalue from the difference between said reference value corrected by saidreference value correcting means and said light intensity controllingdetection value and of outputting said corrected power value to saidoutgoing light amount controlling means.
 12. An information recordingapparatus in accordance with claim 10 or 11, wherein said lightintensity controlling detection signal generating means comprises: alow-pass filter of averaging the output of said reflection light amountdetecting means, a sample-and-hold circuit of detecting the output ofsaid low-pass filter after a predetermined time based on a laser lightmodulation signal, mark area reflection light amount maximum valuegenerating means of obtaining the maximum value of the amount ofreflection light at recording mark areas from a value detected by saidsample-and-hold circuit and the duty ratio of outgoing powercontributing to mark formation, peak power reflection light amountmaximum value generating means of calculating the peak amount ofreflection light at the peak value of light intensity having been set onthe basis of the result of the detection of the amount of reflectionlight at areas, other than the recording mark areas, irradiated withlight at light intensity not contributing to recording mark formation,and a division circuit of dividing said maximum value of the amount ofreflection light at said recording mark areas by the maximum value ofthe peak power amount of reflection light and of generating a lightintensity controlling detection signal.
 13. An information recordingapparatus in accordance with claim 10 or 11, comprising recording mediumtype discrimination means and means of memorizing corrected lightintensity correction table indicating the relationship of the correctionamount of said reference value with respect to said corrected lightintensity in each type of recording medium in advance.
 14. Aninformation recording apparatus in accordance with claim 10 of 11,comprising recording medium type discrimination means and means ofmemorizing light intensity temperature correction table indicating therelationship of the change amount of light intensity suited for markformation with respect to temperature in each type of recording mediumin advance.
 15. An information recording apparatus of recordinginformation in which laser light is applied to a recording medium whiledepending on predetermined information said laser light is modulated andthe intensity of sad light is controlled to form recording mark areas atwhich reflectivity of said recording medium changes, depending on theintensity of said applied light, comprising: outgoing light amountcontrolling means of detecting the amount of outgoing laser light and ofcontrolling the amount of the outgoing laser light so as to obtain apredetermined power value, reflection light amount detecting means ofreceiving reflection light from the recording mark areas of saidrecording medium and of detecting the amount of the reflection light,light intensity controlling detection, signal generating means ofgenerating a light intensity controlling detection signal on the basisof the amount of the detected light of said reflection light amountdetecting means, reference valve generating means of applying light inadvance to said recording medium at predetermined light intensity beforestarting data recording and of generating a light intensity controllingreference value from said light intensity controlling detection signalfrom, light intensity controlling detection value generating means ofgenerating a light intensity controlling detection value from said lightintensity controlling detection signal during data recording, switchingmeans of switching the output of said light intensity controllingdetection signal to said reference value generating means or said lightintensity controlling detection value generating means, stress detectingmeans of detecting stress affecting recording or reproduction on saidrecording medium as the change of light intensity, reference valuecorrecting means of correcting said light intensity controllingreference value depending on said stress, corrected power valuegenerating means of generating a corrected power value from thedifference between said reference value corrected by said referencevalue correcting means and said light intensity controlling detectionvalue and of outputting said corrected power value to said outgoinglight amount controlling means.
 16. An information recording apparatusin accordance with claim 15, comprising recording medium typediscrimination means and means of memorizing stress correction tableindicating the relationship of the correction amount of said referencevalue with respect to said stress in each type of recording medium inadvance.